1. Field of the Invention
The present invention relates to a mask structure for use in forming a desired pattern on a substrate, such as a semiconductor substrate, an exposure method and an apparatus for forming the pattern by using the mask structure, a semiconductor device manufactured by using the mask structure, and a semiconductor device manufacturing method.
2. Description of the Related Art
In manufacturing a device having fine patterns formed thereon, for example, a semiconductor device such as a semiconductor integrated circuit, a micromachine, or a thin-film magnetic head, generally, a desired pattern is formed on a substrate, which serves as a material to be patterned, by radiating light (e.g., visible light, ultraviolet rays, X-rays or the like) onto the substrate via a mask. In manufacturing, for example, a semiconductor integrated circuit, a mask is prepared, the mask corresponding to a desired circuit pattern to be formed on the semiconductor substrate, and the semiconductor substrate, having a resist thereon, is irradiated with light such as X-rays, via the mask. The resist on the substrate is selectively exposed, and the circuit pattern is transferred thereon. Through subsequent etching and film-deposition processes, a desired circuit is formed on the semiconductor substrate. A description will be given below of the manufacturing of the aforementioned device, having fine patterns, with reference to an example in which a semiconductor integrated circuit is formed.
With the recent increases in the density and the operating speed of semiconductor integrated circuits, the line width of integrated circuit patterns has decreased, and conventional semiconductor manufacturing methods need to have a higher performance. For that purpose, under development as a printing apparatus (e.g., an exposure apparatus) is a stepper, which uses exposure light having a shorter wavelength than before, such as light from a KrF excimer laser having a wavelength of 248 nm, light from an ArF excimer laser having a wavelength of 193 nm, or X-rays having a wavelength of 0.2 nm to 15 nm. Furthermore, a chemically amplified resist using an acid catalyst is finding increased use as a resist in transferring a desired pattern onto a material to be patterned.
As the patterns become finer, it will be increasingly difficult to protect against dust generated in the processing. The limitations on the size and amount of normal refuse are becoming more strict, and the sensitivity in processing chemical substances is increasing. Semiconductor integrated circuits are fabricated in a clean room environment, and chemical contamination seriously affects that environment. Chemical contamination is caused by products being decomposed from a resist, substances being produced in resist developing and cleaning processes, adhesives used for the mask, and volatile substances from fixtures, such as the material on walls of the equipment being used.
When exposure is performed for a long time with short-wavelength light, such as far-ultraviolet light or X-rays, in such a chemically contaminated environment, the contamination of the mask surface, namely, deposits thereon, changes the transmittance, reflectance, and scattering properties of the mask. In particular, when a chemically amplified resist is used, an acid generator or acid, and decomposition products evaporate during or after exposure, which accelerates the contamination of the mask. Above all, contamination of the mask is a serious problem in projection exposure using X-rays or the like, because a material to be patterned is spaced from the mask by only several tens of micrometers or less. While these deposits seem to depend on the processing environment, they are not uniform in shape or composition, and the details thereof are not clear. It may be conjectured that the deposits are not produced by a simple photochemical reaction, but by complicated actions of the processes of decomposition, recombination, multi-dimensional reaction, accumulation, crystallization, and the like. Though it may be possible to remove the deposits by cleaning, the cleaning is considerably difficult, particularly in an X-ray mask, since an absorber is shaped with a high aspect ratio (i.e., the height is smaller than the width), and not all deposits can be removed by cleaning. Further, support film in an X-ray mask is weak, because of its small thickness. Therefore, the number of times of cleaning of the mask itself needs to be reduced.
Accordingly, it is an object of the present invention to provide a mask structure in which the number of times of cleaning of a mask is reduced or the need for cleaning is eliminated altogether by preventing contaminants from adhering and accumulating onto the mask surface, so that the life of the mask is thereby extended, and to provide an exposure method and apparatus, a semiconductor device, and a semiconductor device manufacturing method using the mask structure.
In order to achieve the above object, the present invention provides a mask structure including a mask for use in transferring a desired pattern onto a substrate by exposure, a pellicle positioned to cover at least one of a patterned surface of the mask and a surface of the mask opposite to the patterned surface, and a titanium oxide film formed on the surface of the pellicle.
The mask may be a reflective type or a transmission mask.
Preferably, the titanium oxide film is formed on a section of the surface of the pellicle other than a section where light is radiated when the substrate is exposed.
The mask structure is used for exposure using X-rays.
The present invention provides an exposure method including the steps of providing a mask structure having a mask with a desired pattern, a pellicle positioned to cover at least one of a patterned surface of the mask and a surface of the mask opposite to the patterned surface, and a titanium oxide film formed on the surface of the pellicle, and transferring the pattern on the mask onto a material to be patterned by exposure.
Preferably, the transfer by exposure is performed by using a chemically amplified resist on the material to be patterned.
Preferably, the transfer by exposure is performed with X-rays.
The present invention also provides an exposure apparatus for transferring by exposure a pattern on a mask in a mask structure onto a material to be patterned, the mask structure including the mask, and a pellicle positioned to cover at least one of a patterned surface of the mask and a surface of the mask opposite to the patterned surface, the exposure apparatus including mask structure holding means for holding the mask structure, wherein the mask structure has a titanium oxide film formed on the surface of the pellicle, and means for holding the material to be patterned.
The exposure apparatus may further include an auxiliary light source for radiating auxiliary light to the mask structure without affecting the material to be patterned.
The exposure apparatus may further include a mask cassette for storing the mask structure when the material to be patterned is not subjected to exposure, and an auxiliary light source for radiating auxiliary light to the mask structure stored in the mask cassette.
The present invention also provides a semiconductor device manufactured by transferring by exposure a pattern on a mask in a mask structure onto a material to be patterned and processing the patterned material, the mask structure including the mask, a pellicle positioned to cover at least one of a patterned surface of the mask and a surface of the mask opposite to the patterned surface, and a titanium oxide film formed on the surface of the pellicle.
The present invention also provides a semiconductor device manufacturing method including the steps of providing a mask structure having a mask with a desired pattern, a pellicle positioned to cover at least one of a patterned surface of the mask and a surface of the mask opposite to the patterned surface, and a titanium oxide film formed on the surface of the pellicle, transferring by exposure the pattern on the mask onto a material to be patterned, and processing the patterned material.
The present invention also provides a mask structure including a mask for use in transferring a desired pattern onto a substrate by exposure, the mask having an exposure area to be irradiated with an energy beam, and a titanium oxide film formed on the surface of the mask, the titanium oxide film being formed outside the exposure area.
The energy beam may include X-rays.
The present invention also provides an exposure method including the steps of providing a mask structure including a mask with a desired pattern and an exposure area to be irradiated with an energy beam, and a titanium oxide film formed on the surface of the mask, the titanium oxide film being formed outside the exposure area, and transferring by exposure the pattern on the mask onto a material to be patterned.
Preferably, the transfer by exposure is performed by using a chemically amplified resist on the material to be patterned.
Preferably, the transfer by exposure is performed with X-rays.
The present invention also provides an exposure apparatus for transferring by exposure a pattern on a mask in a mask structure onto a material to be patterned, the mask structure having the mask with the pattern and an exposure area to be irradiated with an energy beam, the exposure apparatus including mask structure holding means for holding the mask structure, wherein the mask structure has a titanium oxide film formed on the surface of the mask, and the titanium oxide film is formed outside the exposure area, and means for holding the material to be patterned.
The exposure apparatus may further include an auxiliary light source for radiating auxiliary light to the mask structure without affecting the material to be patterned.
The exposure apparatus may further include a mask cassette for storing the mask structure when the material to be patterned is not subjected to exposure, and an auxiliary light source for radiating auxiliary light to the mask structure stored in the mask cassette.
The present invention also provides a semiconductor device manufactured by transferring by exposure a pattern on a mask in a mask structure onto a material to be patterned and processing the patterned material, the mask structure including the mask having the pattern and an exposure area to be irradiated with an energy beam, and a titanium oxide film formed on the surface of the mask, the titanium oxide film being formed outside the exposure area.
The present invention also provides a semiconductor device manufacturing method, including the steps of providing a mask structure including a mask having a pattern and an exposure area to be irradiated with an energy beam, and a titanium oxide film formed on the surface of the mask, the titanium oxide film being formed outside the exposure area, transferring by exposure the pattern on the mask onto a material to be patterned, and processing the patterned material.
The present invention also provides a mask structure including a mask for use in transferring a desired pattern onto a substrate by exposure, the mask having a film and an absorber pattern formed on the film to be irradiated with an energy beam, and a titanium oxide film formed on the mask, the titanium oxide film being formed on the surface of the film and on the surface of the absorber pattern, which surface excludes the sides of the absorber pattern.
The energy beam may include X-rays.
The present invention also provides an exposure method including the steps of providing a mask structure including a mask with a desired pattern that has a film and an absorber pattern formed on the film, to be irradiated with an energy beam, and a titanium oxide film formed on the mask, the titanium oxide film being formed on the surface of the film and on the surface of the absorber pattern, which surface excludes the sides of the absorber pattern, and transferring by exposure the pattern on the mask onto a material to be patterned.
Preferably, the transfer by exposure is performed by using a chemically amplified resist on the material to be patterned.
Preferably, the transfer by exposure is performed with X-rays.
The present invention also provides an exposure apparatus for transferring by exposure a pattern on a mask in a mask structure onto a material to be patterned, the mask structure including the mask with the pattern that has a film and an absorber pattern formed on the film to be irradiated with an energy beam, the exposure apparatus including mask structure holding means for holding the mask structure, wherein the mask structure has a titanium oxide film formed on the mask, the titanium oxide film being formed on the surface of the film and on the surface of the absorber pattern, which surface excludes the sides of the absorber pattern, and means for holding the material to be patterned.
The exposure apparatus may further include an auxiliary light source for radiating auxiliary light to the mask structure without affecting the material to be patterned.
The exposure apparatus may further include a mask cassette for storing the mask structure when the material to be patterned is not subjected to exposure, and an auxiliary light source for radiating auxiliary light to the mask structure stored in the mask cassette.
The present invention also provides a semiconductor device manufactured by transferring by exposure a pattern on a mask in a mask structure onto a material to be patterned and processing the patterned material, the mask structure including the mask with the desired pattern that has a film and an absorber pattern formed on the film to be irradiated with an energy beam, and a titanium oxide film formed on the mask, the titanium oxide film being formed on the surface of the film and on the surface of the absorber pattern, which surface excludes the sides of the absorber pattern.
The present invention also provides a semiconductor device manufacturing method including the steps of providing a mask structure including a mask with a desired pattern that has a film and an absorber pattern formed on the film to be irradiated with an energy beam, and a titanium oxide film formed on the mask, the titanium oxide film being formed on the surface of the film and on the surface of the absorber pattern, which surface excludes the sides of the absorber pattern, transferring by exposure the pattern on the mask onto a material to be patterned, and processing the patterned material.
The present invention also provides a mask structure including a mask for use in transferring a desired pattern onto a substrate, the mask including an exposure area to be irradiated with an energy beam, and an absorber pattern for the energy beam being formed on the exposure area, and a titanium oxide film formed on the mask, the titanium oxide film being formed outside the exposure area and only on the upper surface of the absorber pattern.
The energy beam may include X-rays.
The present invention also provides an exposure method including the steps of providing a mask structure having a mask with a pattern, the mask including an exposure area to be irradiated with an energy beam, and an absorber pattern for the energy beam being formed on the exposure area, and a titanium oxide film formed on the mask, the titanium oxide film being formed outside the exposure area and only on the upper surface of the absorber pattern, and transferring by exposure the pattern on the mask onto a material to be patterned.
Preferably, the transfer by exposure is performed by using a chemically amplified resist on the material to be patterned.
Preferably, the transfer by exposure is performed with X-rays.
The present invention also provides an exposure apparatus for transferring by exposure a pattern on a mask in a mask structure onto a material to be patterned, the mask structure including the mask having a pattern, an exposure area to be irradiated with an energy beam and an absorber pattern for the energy beam formed on the exposure area, and a titanium oxide film formed on the mask, the titanium oxide film being formed outside the exposure area and only on the upper surface of the absorber pattern, the exposure apparatus including mask structure holding means for holding the mask structure, and means for holding the material to be patterned.
The exposure apparatus may further include an auxiliary light source for radiating auxiliary light to the mask structure without affecting the material to be patterned.
The exposure apparatus may further include a mask cassette for storing the mask structure when the material to be patterned is not subjected to exposure, and an auxiliary light source for radiating auxiliary light to the mask structure stored in the mask cassette.
The present invention also provides a semiconductor device manufactured by transferring by exposure a pattern on a mask in a mask structure onto a material to be patterned and processing the patterned material, wherein the mask structure includes the mask having the pattern, an exposure area to be irradiated with an energy beam and an absorber pattern for the energy beam formed on the exposure area, and a titanium oxide film formed on the mask, the titanium oxide film being formed outside the exposure area and only on the upper surface of the absorber pattern.
The present invention also provides a semiconductor device manufacturing method including the steps of providing a mask structure including a mask having a pattern, an exposure area to be irradiated with an energy beam and an absorber pattern formed on the exposure area for the energy beam, and a titanium oxide film formed on the mask, the titanium oxide film being formed outside the exposure area and only on the upper surface of the absorber pattern, transferring by exposure the pattern on the mask onto a material to be patterned, and processing the patterned material.
The present invention also provides an exposure apparatus for transferring by exposure a desired pattern on a mask in a mask structure onto a material to be patterned, the mask structure including the mask covered or not covered with a pellicle, and a titanium oxide film formed thereon, the exposure apparatus including a first chamber in which the pattern is transferred onto the material to be patterned through exposure by using the mask structure, and a second chamber containing an auxiliary light source for irradiating the titanium oxide film to cause the titanium oxide film to act as a photocatalyst.
Preferably, the second chamber is used to store the mask structure.
Further objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiments with reference to the attached drawings.